A disk motor described in Japanese Patent No. 3636700 mainly includes an output shaft, substantially circular disk-shaped coil disks which are fixed to the output shaft and on which coil patterns are printed, commutators connected to the coil patterns, magnets disposed so as to face the coil patterns and brushes for supplying electric current to the commutators.
The rotation speed of the disk motor is determined by a voltage supplied from the brushes, an electric current of the disk motor, the coil patterns of the coil disks, a magnetic flux of the magnets and the number of brushes (the number of poles). When the voltage supplied from the brushes and the electric current of the stator motor are constant, the disk motor can be set to a desired rotation speed by changing the coil patterns of the coil disks, the magnetic flux of the magnets, and the number of brushes.
A laminated coil substrate described in JP-A-2006-157985 has a construction in which dummy electrodes are formed on the same plane as coil electrodes, and an area where a space between the coil electrodes and the dummy electrodes becomes the least is sandwiched in a laminating direction together with part of the coil electrodes and part of the dummy electrodes by reinforcement electrodes which are laminated on the laminated coil substrate. By adopting this construction, the mechanical strength of the laminated coil substrate is attempted to be enhanced. The laminated coil substrate is a sintered substrate formed by sintering laminated ceramic green sheets.
A multi-layer substrate described in JP-A-H09-232162 prevents an epoxy resin of a bonding prepreg, which melts due to heat produced when substrates are laminated and bonded together, from flowing out between the substrates by providing a surrounding pattern which surrounds a coil pattern at the periphery of the coil pattern.
In a thin laminated coil described in JP-A-H09-45531, a dummy pattern which is electrically disconnected from a coil pattern is provided on at least an upper surface and a lower surface of double-faced substrates which face each other. According to this construction, an inter-layer sheet member (a prepreg) can be formed thin by a dummy pattern which is formed on a portion where the inter-layer sheet member is originally interposed. This provides not only an advantage that a loading amount of a resin which is to be impregnated in the inter-layer sheet member can be reduced but also an advantage that the dummy pattern forms a dam to prevent the leakage of the resin impregnated in the inter-layer sheet member to the periphery thereof.
JP-A-2004-80996 discloses a technique to increase the cooling and radiating performance of stator coils by increasing the cooling and radiating surface areas of the stator coils in a commutator motor.